Mineral oils in food grade paper and paperboard products primarily originate from printing inks and grease and certain other hydrocarbon-based chemistries used during the manufacturing, paperboard converting, and packaging process. Old corrugated container (OCC) makes up a significant part of the recycled waste paper stream. Some of the recycling mills may also use mixed papers that may contains over 50-90% ONP/OMG (old newspaper and old magazine). OCC recycling mills are operated very differently than conventional mixed paper recycling mills. As a result, most printing inks are left in the recycled pulping and papermaking processes and end up in the recycled paper products. This is one of the main reasons why there is a high content of residual printing inks, wax, sizing and coating chemicals and other impurities on the recycled fibers in OCC recycling mills. These impurities may end up in many food grade papers and paperboard, such as the food packaging boxes for cereal, pizza, and frozen food.
Mineral oils (mineral oil hydrocarbons, MOH) are the by-products of petroleum distillation of hydrocarbons. The major components of the mineral oils are mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOAH). MOSH includes paraffins (linear or branched alkanes) and naphthenes (alkyl-substituted cyclo-alkanes), and MOAH (mainly alkyl-substituted polyaromatic hydrocarbons). In general, MOH are considered medically problematic, with some forms likely more problematic than others (EFSA, Scientific Opinion on Mineral Oil Hydrocarbons in Food, EFSA Journal 2012; 10 (6): 2704). For example, MOAH are considered more problematic than MOSH, MOH with rings are generally considered more problematic than MOH without rings, and more saturated MOH are considered more problematic than less saturated MOH.
Zurich's Official Food Control Authority has published two studies on the issue of the mineral oil migration (Biedermann et al. (2011), Mineral oil contents in paper and board recycled to paperboard for food packaging. Packag. Technol. Sci., 24: 61-73. doi: 10.1002/pts. 914; Biedermann, M. and Grob, K. (2010), Is recycled newspaper suitable for food contact materials? Eur. Food Res. Technol., 230: 785-796) which highlighted the inclusion of mineral oil in old newspapers in recycled paper and board as the main source of the potentially harmful oils. A survey of packaging of the German market identified mineral oil contamination in 119 samples of dry food packed in paperboard boxes (Vollmer et al., Eur Food Res Technol (2011) 232: 175-182). An analytical method for detecting the mineral oil content in paperboard packaging has been developed (Bundesinstitut für Risikobewertung (BfR), 2011). A substantial proportion of the offset printing inks applied to food packaging contained mineral oil, often including 15-20% MOAH (Vollmer et al., European Food Research and Technology, 232, 175-182 (2011)).
When foods in recycled board are densely packed into larger boxes or onto pallets, most of the hydrocarbons up to n-C20 may migrate into the packed food within a few weeks and those up to n-C28 at a slightly lower rate. The main sources of mineral oils in recycled paper are the inks used for printing newspapers: newspapers may contain roughly 3,000 mg/kg mineral oil hydrocarbons <n-C28. These mineral oils fall into classes for which JECFA established a tolerable daily intake of 0.01 mg/kg body weight. The oils found in recycled board contain 15-25% aromatic compounds, predominantly with 1-3 aromatic rings.
Since freshly packed foods are usually packed into larger transport boxes and stacked onto pallets, most of the mineral oil migrates inwards into the foods if not blocked by a barrier layer between the food and the print layer. Contamination of dry foods in paperboard boxes at concentrations sometimes exceeding 100 mg/kg was shown in studies by Grob et al. (Food Additives and Contaminants, 8, 437-446 (1991)) as well as Droz and Grob (Zeitschrift Fur Lebensmittel-Untersuchung Und-Forschung a-Food Research and Technology, 205, 239-241 (1997)). It was also shown that internal paper or polyethylene bags had little barrier effect.
Some of the foods packaged in paper and board packaging materials are consumed without further processing, such as cereals. Other foods, such as rice, are cooked before consumption. However, cooking in boiling water may remove only a part of the migrated MOH, perhaps because the MOH are located in the food matrix pores and water entering these pores is an almost perfect barrier to prevent MOH to be transferred into the boiling water (Biedermann-Brem and Grob, European Food Research and Technology 232, 1035-1041 (2011)).
Although it has been suggested that the problem of mineral oils in food packaging may be solved by using only virgin fiber for manufacture of food packaging, this is not cost-effective or practical. For example, the cost of virgin fiber is consistently many hundreds of dollars more expensive than recycled pulps. It has been estimated that exclusive use of virgin fiber for food packaging would require a doubling in worldwide tree production dedicated for paper packaging use. Increased use of virgin fiber would also reduce the demand for recycled paper with the result that more waste paper will end up in landfills or be incinerated. Finally, virgin fiber may not eliminate the problem of mineral oil in food as the process equipment and processing chemistries used for paper and paperboard production and conversion and in the packing process also contribute to the mineral oil levels in food packages. In one study, the initial concentration of MOSH<n-C24 in paperboard, the mean and maximum concentrations calculated for boxes largely consisting of recycled fibers (n=107), were 433 mg/kg paper and 1820 mg/kg paper respectively (Vollmer et al. (2011)). In boxes made of virgin fibers (n=13) the corresponding concentrations were 175 mg/kg paper and 402 mg/kg paper.
There is a need to produce pulp, board, and paper having reduced levels and less problematic forms of residual mineral oils.
It is therefore an object of this invention to provide enzyme compositions to treat the paper pulp and wastepaper during the recycling or papermaking process for reduced levels and/or less problematic forms of mineral oil hydrocarbons in processed pulp and paper products.
It is therefore an object of this invention to provide enzyme compositions to break down and/or modify the structure of mineral oil hydrocarbons for reduced levels and/or less problematic forms of mineral oil hydrocarbons in processed pulp and paper products.
It is therefore an object of this invention to provide enzyme compositions to mobilize and liberate mineral oil hydrocarbons in pulp for reduced levels and/or less problematic forms of mineral oil hydrocarbons in processed pulp and paper products.
It is therefore an object of this invention to provide a method using such enzyme compositions to break down and/or modify the structure of mineral oil hydrocarbons for reduced levels and/or less problematic forms of mineral oil hydrocarbons in processed pulp and paper products.
It is therefore an object of this invention to provide a method using such enzyme compositions to mobilize and liberate mineral oil hydrocarbons in pulp for reduced levels of mineral oil hydrocarbons in processed pulp and paper products.
It is therefore an object of this invention to provide a method using such enzyme compositions for reduced residual mineral oil levels in processed pulp and products.
It is therefore an object of this invention to provide a method using enzyme compositions and process steps to mobilize and liberate mineral oil hydrocarbons in pulp for reduced levels of mineral oil hydrocarbons in processed pulp and paper products.
It is also an object of this invention to provide processed pulp having lower levels of mineral oil hydrocarbons.
It is also an object of this invention to provide paper products made from pulp having lower levels of mineral oil hydrocarbons.